Answer:
456
Step-by-step explanation:
Let X be the SATscore scored by the students
Given that X is normal (1000,200)
By converting into standard normal variate we can say that
is N(0,1)
To find the top 10% we consider the 90th percentile for z score
Z 90th percentile = 1.28
i.e. only students who scored 456 or above only should be considered.